In the field of geophysical exploration for example, non-intrusive techniques have been sought and developed as a supplement or an alternative to conventional in-situ testing techniques involving boring because these techniques are non-destructive. In some cases where boring is not feasible, for example in granular soils, such non-intrusive techniques are the only way to explore the underground. Also, they generally are most cost-effective.
Non-intrusive techniques are also used for exploring a medium situated under a surface in various other fields, for example, for assessing the wear conditions of roads, of bridges, of bar joints in buildings, of concrete walls, etc, or for detecting subsurface pockets in mining or military applications.
Interestingly, surface waves, and especially Rayleigh waves, are very useful in the field of non-intrusive testing. One of the well known method in the art is Spectral Analysis of Surface Wave (“SASW”), for instance, which makes use of surface waves for determining shear velocity profiles of the underground without intrusion. This method involves a pair of sensors, at least one source of impulses, and a signal processing system.
Although such a technique using surface waves permits exploration of a broad range of thickness of soils, by changing the distance between the two sensors and by using different sources of impulses, in the case of SASW discussed hereinabove for instance, its operation generally requires actions from a highly skilled worker expert in the field in order to obtain useful information on the subsurface medium under investigation.
Therefore, in spite of the efforts in the field, there is still a need for a system allowing profiling of a medium under a surface, comprising sensors, a generator of impulses and a user-computing interface, and permitting collecting, analyzing, and processing the data for display and use by a non-expert.